So the solution would be:
The first thing that is not clear to me is about , with I've got: which gives 0/0. I know from the books that its well defined for , so I just accepted this fact. But now, in incise b) I have to evaluate y(0), which is not defined.

So the solution would be:
The first thing that is not clear to me is about , with I've got: which gives 0/0. I know from the books that its well defined for , so I just accepted this fact. But now, in incise b) I have to evaluate y(0), which is not defined.

Since you want and is undefined (it as ) you will need to choos . Then pick as to make .